Methods and compositions for removing residues and substances from substrates using environmentally friendly solvents

ABSTRACT

Environmentally friendly solvents used to dissolve or remove residues and/or substances from substrates wherein the residue and/or substance is contacted with a Generally Recognized As Safe solvent to dissolve the residue and/or substance in the solvent followed by the extraction of the residue and/or substance from the solvent such as by contact with carbon dioxide.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/336,045, filed Dec. 16, 2008, now abandoned, which is a continuationof U.S. patent application Ser. No. 11/634,754, filed Dec. 6, 2006 nowU.S. Pat. No. 7,465,395 which is a continuation of U.S. patentapplication Ser. No. 10/374,119, filed Feb. 25, 2003 (now abandoned),which claims the benefit of, and incorporates herein by reference intheir entireties, the following United States Provisional Applications:U.S. Provisional Application No. 60/359,935, filed Feb. 27, 2002U.S.Provisional Application No. 60/359,826, filed Feb. 27, 2002; U.S.Provisional Application No. 60/359,976, filed Feb. 27, 2002; and U.S.Provisional Application No. 60/359,975, filed Feb. 27, 2002.

FIELD OF THE INVENTION

This invention relates to methods and compositions for removing residuesand substances from substrates and/or compounds.

BACKGROUND OF THE INVENTION

Various wanted and unwanted substances or residues may be removed fromobjects or substrates using various methods. For instance, chemicalsolvents may be used to remove unwanted residues from machinery,unwanted particles from products, or otherwise. Solvents may also beused to extract residues or substances from chemical compositions,products, or materials. For instance, a solvent may be used to separatea particular chemical compound from a mixture of chemical compounds.However, many of the solvents typically used by industry are notenvironmentally friendly. In fact, many of the solvents are hazardousmaterials and are expensive to use, maintain, control, and dispose of.

As one example, solvents are used to remove the build-up of solid andliquid petroleum residues and substances from substrates such asprocessing equipment. The build-up of oil residues such as asphalt andasphalt-related liquids (e.g., tar, pitch, and tack) on processingequipment utilized in petroleum and chemical processing, storage, andtransport industries, as well as equipment used in highway and roadconstruction, has long been problematic. After a certain level ofbuild-up occurs, the equipment is often no longer capable of being usedfor its intended purpose. Accordingly, it is typically necessary toclean such equipment. Diesel fuel or a similar type of fuel has beenused in the past for cleaning construction equipment. However, the useof these solvents has largely fallen into disfavor due to heightenedenvironmental concerns. See e.g., Federal Water Pollution Control ActAmendments of 1972 (PL 92-500) Section 311(b)(1).

Another alternative is to employ organic solvents. Such solvents alsopose potential environmental concerns. For instance, chlorinatedsolvents such as 1,1,1-trichloroethane or methylene chloride may be usedto remove petroleum residues or substances from substrates. Moreover,notwithstanding any potential benefits associated therewith, thesesolvents are typically less than fully effective in removing petroleumresidue. More specifically, these solvents are often not able to removehard-to-dissolve petroleum residue fractions such as asphaltenes.Accordingly, these fractions are typically removed by employinglabor-intensive efforts that are often time-consuming and expensive.

As another example, there is a current increasing interest in extractingwanted tar sand oil from its naturally occurring ores. Such ores aresubstantial underutilized sources of fossil fuels, particularly, forexample, in Venezuela, Canada, and the United States. As crude oilreserves become relatively heavier, the need and consequent demand forrecovering bitumen fractions from inorganic substrates (e.g., tar sands)increases.

Examples of methods currently employed in the extraction of tar sandsinvolve the use of hot water, organic solvents, or petroleumdistillates. During hot water extraction, emulsions are formed that areoften difficult to break and to efficiently separate bitumen from water.These processes usually result in the generation of relatively highquantities of wastewater, termed “extraction tailings”. Methods ofwastewater treatment are often needed to allow a production site toattempt to comply with environmental regulations. Extractions withorganic solvents or petroleum distillates often utilize materials ofrelatively high capital value to obtain bitumen of a lower capitalvalue. Moreover, solvent extraction typically requires significantexpenditures of equipment and energy to separate extracted bitumen fromthe organic solvent. As a result, it is extremely difficult on acommercial scale to employ extraction methods employing organicsolvents.

The treatment and remediation of asphaltenic deposits occurring indifferent places in the production, refining, and transportation ofcrude oil is also desirous. Many crude oils are prone to formasphaltenic deposits. These deposits are detrimental to the productivityof the reservoir (as they clog the porosity of the pay zone), throughputof the pipeline, efficiency of the desalter and gas-liquid separator,and the storage capacity of a storage tank. Currently these asphaltenicdeposits are either removed mechanically, or by employing expensive andenvironmentally irresponsible solvents.

Therefore, it is desirous to develop and use compositions and methodsfor removing residues or substances from substrates without theemployment of expensive manual processes or expensive, and oftenenvironmentally hazardous, organic solvent extraction processes.

SUMMARY OF THE INVENTION

Embodiments of the present invention include compositions and methodsfor extracting or removing residues and/or substances from substrates.In certain embodiments, the residues and/or substances are removed froma substrate using an environmentally responsible solvent, for example, aGenerally Recognized As Safe (also known as “GRAS”) solvent. Preferablythe GRAS solvent is miscible with carbon dioxide. Once removed, theresidues or substances may be removed from a GRAS solvent, such as bycontacting the GRAS solvent with carbon dioxide to separate any residueand/or substance from the GRAS solvent. For example, a petroleum residuemay be removed from a substrate in the form of a tool by contacting thetool with a GRAS solvent composition, and the GRAS solvent compositioncould be separated from the dissolved or collected petroleum residue bycontacting the GRAS solvent with carbon dioxide and precipitating thepetroleum residue.

The methods and compositions of various embodiments of the presentinvention may be used to remove or dissolve petroleum-based residues orsubstances from substrates. In various embodiments, the inventioncomprises a method of removing petroleum residue from a substrate. Themethod comprises contacting the substrate with a solvent such that thepetroleum residue separates from the substrate and is dissolved in thesolvent. The solvent may include a GRAS solvent such as anester-containing solvent. For example, a residue on a substrate may beseparated from the substrate (e.g., a tool, tar sand, aqueous stream,etc.) by contacting the substrate with a benzoic acid ester-containingsolvent such that the petroleum residue separates from the substrate andis dissolved in the benzoic acid ester-containing solvent. The solventmay be used to remove residues and/or substances from organic orinorganic substrates.

In other embodiments of the invention, the quantity of bitumen presentin a petroleum residue sample may be determined using the compositionsand methods of the present invention. A petroleum sample may becontacted with a GRAS solvent to remove bitumen from the sample. Theweight of the bitumen extracted from the petroleum sample may bedetermined from weight measurements of the sample before and after beingcontacted with the GRAS solvent. Alternatively, the bitumen extracted bythe GRAS solvent from the sample may be extracted from the GRAS solventby contact with carbon dioxide and weighed or otherwise measured.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The invention can be more readily ascertained from the followingdescription of the invention when read in conjunction with theaccompanying drawings in which:

FIG. 1 compares precipitated bitumen (weight percent) versus pressure atdifferent temperatures, and corresponds to Example 8.

FIG. 2 compares precipitated bitumen (weight percent) versus preserve atdifferent bitumen concentration, and corresponds to Example 9.

FIG. 3 compares precipitated bitumen (weight percent) versus carbondioxide density, and corresponds to Example 10.

FIG. 4 compares precipitated bitumen (weight percent) versus pressure atdifferent solvent to carbon dioxide ratios, and corresponds to Example11.

FIG. 5 compares precipitated bitumen (weight percent) versus pressureusing single batch extraction and multiple batch extraction at 25° C.,and corresponds to Example 12.

FIG. 6 compares precipitated bitumen (weight percent) versus pressureusing single batch extraction and multiple batch extraction at 35° C.,and corresponds to Example 13.

FIG. 7 compares precipitated bitumen (weight percent) versus pressureusing single batch extraction and multiple batch extraction at 50° C.,and corresponds to Example 14.

FIG. 8 compares precipitated bitumen (weight percent) versus pressureusing single batch extraction and multiple batch extraction at 80° C.,and corresponds to Example 15.

FIG. 9 compares precipitated bitumen (weight percent) versus pressureusing single batch extraction and multiple batch extraction at 100° C.,and corresponds to Example 16.

FIG. 10 compares the amount of extracted bitumen as a function of bothtemperature and pressure, and corresponds to Example 18.

FIG. 11 compares the amount of extracted bitumen as a function of bothtemperature and pressure, and corresponds to Example 19.

DETAILED DESCRIPTION OF THE INVENTION

This invention may, however, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein;rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the inventionto those skilled in the art and optionally collected or removed.

In general, the present invention provides a method of dissolving apetroleum-based substance. The petroleum-based substance is contactedwith a carbon dioxide miscible solvent and a portion of thepetroleum-based substance is dissolved. The dissolved petroleum-basedsubstance is separated and contacted with carbon dioxide such that thepetroleum-based substance is precipitated.

For example, a substrate is contacted with a carbon dioxide misciblesolvent to extract or remove a residue or desired substance from thesubstrate. A substrate may be fed to a first reaction chamber to which asolvent is also fed. The solvent contacts the substrate within thereaction chamber and dissolves or otherwise separates a residue ordesired substance from the substrate. A product stream of the solventwith dissolved and/or suspended residue or substances removed from thesubstrate in the first reaction chamber may then be fed to a secondreaction chamber where the solvent is contacted with carbon dioxide toremove any residue dissolved or otherwise suspended in the solvent fromthe solvent.

In various embodiments, the invention provides a method of removingpetroleum residue from a substrate. A substrate may be an organicsubstrate, an inorganic substrate, or a combination thereof. The methodcomprises contacting the substrate with a solvent such that thepetroleum residue separates from the substrate and is dissolved in thesolvent. The solvent, in addition to being carbon dioxide miscible, ispreferably an environmentally friendly solvent such as a solvent that isGenerally Recognized As Safe. Such solvents are also known as “GRASsolvents” and such term is used throughout the description to representsuch solvents. For instance, ester-containing solvents such as benzoicacid ester-containing solvents are representative GRAS solvents that maybe used as compositions of various embodiments of the present inventionor with the methods of various embodiments of the present invention.

The term “substrate” is to be construed broadly and refers to variousliquid materials, solid materials, combinations thereof, including,without limitation, semi-liquid and/or semi-solid materials, whichcontain a substance or residue to be removed, dissolved or extracted. Invarious embodiments, the residue may be “on” the surface of thesubstrate, may be embedded, entrained or contained within the substrate,or may be partially embedded, entrained or contained within thesubstrate. Inorganic (e.g., metal and ceramic) and organic substrates,as well as alloys and composites thereof, are well within the scope ofthe invention. In various embodiments, for example petroleum substancerecovery processes, exemplary substrates may be present in and/or onarticles of manufacture employed in the petroleum refining, storage, andtransportation fields, including, without limitation, cleaning storagetanks, electrostatic desalters, API separators, slop oil tanks,electrostatic precipitators, crude oil storage tanks, gas separators,pipelines, reservoirs, and the like.

The term “inorganic substrate” is to be construed broadly and refers tovarious materials that contain a petroleum residue. In particular, thepetroleum residue may be “on” the surface of the substrate, may beembedded, entrained or contained within the substrate, or may bepartially embedded, entrained or contained within the substrate.Inorganic substrates include those formed from or containing inorganiccompounds such as, without limitation, mineral ores, mineral oxides,rock, clay, silica, as well as combinations thereof. Preferred inorganicsubstrates are those that are tar or oil sands and oil shales.

The term “dissolved in the solvent” is to be broadly construed to referto residue being solubilized or entrained in a solvent. The term mayrefer to a one-phase solution or a multi-phasic, or biphasic, dispersionor suspension in the solvent. Accordingly, the term is intended toencompass all embodiments in which a residue could be fully soluble,partially soluble, or insoluble in a solvent according to embodiments ofthe present invention.

The term “tar or oil sands” is defined broadly as porous sandstonestructures occurring on the surface and depths well below the surfacethat are impregnated with heavy, viscous black crude oil that typicallycannot be retrieved well by conventional production techniques. For thepurposes of the invention, the terms “bituminous sands” or “oil sands”may be used as an alternative to tar sands. Tar sands typically containa sizeable proportion of bitumen, containing primarily asphaltenes andheavy low volatility fractions of maltha, typically together with asubstantial percentage of sulfur and heavy metals.

The term “oil shale” is to be broadly construed and typically refers toextensive sedimentary rock deposits typically containing a relativelyhigh percentage of kerogen.

For the purposes of the invention the term “petroleum residue” is to bebroadly construed and includes, without limitation, material that istypically present in various applications that are related to petroleumproducts (e.g., crude oils, asphaltic residues, coal tar, waxes, resins,petroleum sludges, and tank bottoms), and any number of by-products. Forthe purposes of the invention, “petroleum residue” encompasses heavypetroleum fractions preferably having a boiling point of at least 150°C. or 200° C., more preferably at least 340° C., which includes amixture of paraffinic and aromatic hydrocarbons along with heterocycliccompounds containing sulfur, nitrogen, and oxygen. Asphalt, as well asresidues and related materials thereof, also are construed as beingencompassed by the term “petroleum residue” for the purposes of theinvention. The asphalt content varies considerably as known by oneskilled in the art. For example, in one embodiment, the asphalt contentmay vary from 3 to 8 percent. In another embodiment, the asphalt contentmay vary from 4 to 6 percent. The asphalt content may be higher orlower. For example, in a roofing application, the asphalt content may behigher.

As understood by one skilled in the art, asphalt is a product of crudeoil refining. In an exemplary asphalt production process, crude oil isdistilled in a primary flash distillation column, the residue of thisprocess is introduced to an atmospheric distillation column. The residueof the atmospheric distillation process is typically distilled underreduced pressure (e.g., vacuum distillation), and the residue is termedasphalt. The asphalt produced from the vacuum distillation of crude oiltypically has softening points ranging from 25° C. to 55° C. Asphalts ofintermediate softening points may be made, for example, by blending withhigher and lower softening point asphalts. If the asphalt has a lowsoftening point, it can be hardened by further distillation with steamor by oxidation (e.g., air blowing). Furthermore, asphalt can be alsoproduced by propane deasphalting in the production of lubricating oilsfrom crude oil residual. The asphalt produced by propane deasphaltingmay have a softening point of about 90° C. Softer grades may be made byblending the hard asphalt with the extract obtained in the solventtreatment of lubricating oils.

In general, “asphalt” may be defined as the residue of mixed-base andasphalt-base crude oils. For the most part, it is difficult to distilleven under the highest vacuum, because such temperatures which are oftenemployed tend to promote formation of coke. For the most part, asphaltshave complex chemical and physical compositions that usually vary withthe source of the crude oil and are considered dispersions or solutionsof particles or aggregates, called asphaltenes, in a high-boiling fluidcomposed of oil and resins. Asphaltene content in petroleum residuesvary widely as known. As appreciated in the art, the nature of theasphalt is often determined by such factors as the nature of the medium(e.g., paraffinic or aromatic), as well as the nature and proportion ofthe asphaltenes and of the resins. The polar and fused ring portions ofthe asphaltenes have been suggested to be lyophobic; the resins areconsidered to be lyophilic, and the “interaction” of the resins with theasphaltenes is believed to be responsible for asphaltene solvation ordispersion, which seems to exercise marked control on the quality of theasphalt. The asphaltenes vary in character, but typically are either ofsufficiently high molecular weight or aggregate size to requiresolvation or dispersion by the resins. Various asphaltic materials maybe removed from substrates by the various embodiments of the presentinvention. As an example, cutbacks and emulsions compose liquidasphalts. A cutback may be defined as a cement that has been liquefiedwith solvents such as, for example, naptha or gasoline or kerosene.Emulsified asphalts are mixtures of asphalt cement, water and anemulsifying agent.

An important class of petroleum residue is bitumen. As known in the art,“bitumen” is defined as a mixture of hydrocarbons occurring in thepetroleum. Other components such as, for example, oils, waxes, resins,pitch and tack are typically present in the petroleum residue. Bitumenis also well understood to be the liquid fuel product obtained byextraction of petroleum from tar or oil sands. Another component of thepetroleum residue is the asphaltene fraction, which is present as partof the bitumen. For the purposes of this invention, the term“asphaltenes” is defined to be components of the high boiling pointfraction of the crude oil which are composed of polynuclear aromatichydrocarbons of molecular weights ranging from 500 to 2000 or greaterand aggregate molecular weights of up to 20,000 joined by alkyl chains.See, e.g., Hawley's Condensed Chemical Dictionary, 12^(th) Ed., RichardJ. Lewis, Sr., Editor, (1993), p. 101.

As discussed above, a solvent according to an embodiment of the presentinvention may include an ester contained GRAS solvent, and for example abenzoic acid ester-containing solvent. The benzoic acid ester containingsolvent comprises one or more benzoic acid esters. Exemplary benzoicacid esters include, without limitation, methyl benzoic acid ester,ethyl benzoic acid ester, n-propylbenzoic acid ester, isobutylbenzoicacid ester, n-butyl benzoic acid ester, tert-butyl benzoic acid ester,isomers of pentylbenzoic acid ester, isopropylbenzoic acid ester, andmixtures thereof.

An exemplary benzoic acid ester is isopropylbenzoic acid ester (“IPB”).Preferably, in various embodiments, the benzoic acid ester-containingsolvent contains at least about 70, 80, 85, 90, 95, or 99 percent byweight of the one or more benzoic acid esters. In one preferredembodiment, the benzoic acid ester-containing solvent contains fromabout 90 to about 95 percent by weight of the one or more benzoic acidesters. The benzoic acid ester may contain other components, processingaids, and the like as deemed appropriate by one skilled in the art.

The benzoic acid ester-containing solvent is potentiallyenvironmentally-advantageous in that, in a preferred embodiment, it hasa flash point (open cup) greater than about 98° C. (e.g., 98.9° C.). Thebenzoic acid ester-containing solvent is potentially nontoxic, readilybiodegradable, and has a UK OCNS rating category E which is the leasttoxic category of this method of evaluating toxic chemicals, meanwhilecategory A being the most toxic. Any compound rated from C-E typicallysignifies that the material may be readily biodegradable and may benonbioaccumulative (Offshore Chemical Notification Scheme).

In one preferred embodiment, the benzoic acid ester-containing solventis substantially devoid of surfactant; in any event, as an example, thebenzoic acid ester-containing solvent may, in certain preferredembodiments, contain no more than about 0.01 weight percent ofsurfactant. Accordingly, in embodiments which employ little if anysurfactant, the benzoic acid ester-containing solvent is non-foaming. Inother preferred embodiments, the benzoic acid ester-containing solventis non-ionic. In other embodiments, the benzoic acid ester-containingsolvents may be free or essentially free of phosphate-acids,halogen-containing compounds (e.g., chlorine-containing solvents such asmethylene chloride and 1,1,1-trichloroethane), and/or petroleumdistillates, as well as combinations thereof, e.g., preferably 1, 0.5,or 0.1 percent by weight of such solvents. Advantageously, afterextraction in one embodiment, the concentration of petroleum residue inthe benzoic acid ester-containing solvent may range from about 5 toabout 30 weight/volume (wt/vol) percent.

Other components may be used in the benzoic acid ester-containingsolvent, the selection of which is known to one skilled in the art. Forexample, limonene, terpeneoids, alkyl phthalate esters, alkyl esters ofcyclohexanoic acid, glycerol fatty acid esters (diglycerides andtriglycerides), glycerol, ethylene glycol, polyethylene glycol,propylene glycol, alkanolamines, such as: ethanolamine, diethanolamine,triethanolamine, propanolamine, and butanolamine may be used.

Other GRAS solvents may include other ester-containing solvents. In apreferred embodiment, the ester is an “aromatic ester compound” whichmay be defined as an ester-containing substituent attached to asubstituted or an unsubstituted aromatic ring. Exemplary ester compoundsinclude, without limitation, salicylic acid esters, cinnamic acidesters, propionic acid esters, butyric acid esters, pentanoic acidesters, and hexanoic acid esters.

Exemplary salicylic acid esters include, without limitation, methylsalicylate, ethyl salicylate, n-propyl salicylate, isobutyl salicylate,n-butyl salicylate, tert-butyl salicylate, isomers of pentyl salicylate,isomers of hexyl salicylate, isomers of heptyl salicylate, isopropylsalicylate, and mixtures thereof.

Exemplary cinnamic acid esters include, without limitation, methylcinnamate, ethyl cinnamate, n-propyl cinnamate, isobutyl cinnamate,n-butyl cinnamate, tert-butyl cinnamate, isomers of pentyl cinnamate,isomers of hexyl cinnamate, isomers of heptyl cinnamate, isopropylcinnamate, benzyl cinnamate, and mixtures thereof.

Exemplary propionic acid esters include, without limitation, phenylpropionate, benzyl propionate, hydroxyphenyl propionate, methyl phenylpropionate, isobutyl phenyl propionate, n-butyl phenyl propionate,tert-butyl phenyl propionate, isomers of pentyl phenyl propionate,isomers of hexyl phenyl propionate, isomers of heptyl phenyl propionate,isopropyl phenyl propionate, and mixtures thereof.

Exemplary butyric acid esters include, without limitation, phenylbutyrate, benzyl butyrate, hydroxyphenyl butyrate, methyl phenylbutyrate, isobutyl phenyl butyrate, n-butyl phenyl butyrate, tert-butylphenyl butyrate, isomers of pentyl phenyl butyrate, isomers of hexylphenyl butyrate, isomers of heptyl phenyl butyrate, isopropyl phenylbutyrate, and mixtures thereof.

Exemplary pentanoic acid esters include, without limitation, phenylpentanoate, benzyl pentanoate, hydroxyphenyl pentanoate, methyl phenylpentanoate, isobutyl phenyl pentanoate, n-butyl phenyl pentanoate,tert-butyl phenyl pentanoate, isomers of pentyl phenyl pentanoate,isomers of hexyl phenyl pentanoate, isomers of heptyl phenyl pentanoate,isopropyl phenyl pentanoate, and mixtures thereof.

Exemplary hexanoic acid esters include, without limitation, phenylhexanoate, benzyl hexanoate, hydroxyphenyl hexanoate, methyl phenylhexanoate, isobutyl phenyl hexanoate, n-butyl phenyl hexanoate,tert-butyl phenyl hexanoate, isomers of pentyl phenyl hexanoate, isomersof hexyl phenyl hexanoate, isomers of heptyl phenyl hexanoate, isopropylphenyl hexanoate, and mixtures thereof.

Preferably, the ester-containing solvent contains at least about 70, 85,90, 95, or 99 percent by weight of the one or more of the esters. In onepreferred embodiment, the ester-containing solvent contains from about70 to about 95 percent by weight of the ester. The ester-containingsolvent may contain other components, processing aids, and the like asdeemed appropriate by one skilled in the art.

The method of removing petroleum residue from a substrate may encompassnumerous steps. In one embodiment, for example, the method furthercomprises the step of contacting the carbon dioxide miscible or GRASsolvent with a fluid comprising carbon dioxide, wherein the petroleumresidue is recovered in the fluid such that the carbon dioxide miscibleor GRAS solvent is separated from the petroleum residue, e.g., at least95 weight percent of the carbon dioxide miscible or GRAS solvent isseparated from the petroleum residue. Furthermore, the method of theinvention may further comprise the step of recycling the carbon dioxidemiscible or GRAS solvent for further use. Moreover, in anotherembodiment, the invention may encompass the step of subjecting thesubstrate to a fluid or gas comprising carbon dioxide (“CO₂”) orhydrocarbon gas to remove a portion of the petroleum residue from thesubstrate, with the subjecting step occurring prior to the step ofcontacting the substrate with the carbon dioxide miscible or GRASsolvent.

In one embodiment, bitumen can be removed and recovered from a petroleumresidue. The substance containing bitumen is contacted, preferably in areaction vessel, with a GRAS solvent. At least a portion of the bitumenis dissolved in the solvent. The dissolved bitumen and solvent iscontacted with CO₂ to precipitate the bitumen from the solvent. Theprecipitated bitumen is then recovered. The weight of bitumen extractedmay be determined from weight measurements of the sample before andafter contacting with the GRAS solvent. The solvent may remove fromabout 5, 10, 20, 30, or 40 to about 60, 70, 80, 90, or 100 percent byweight of bitumen from a petroleum residue based on the weight ofbitumen that is present in the residue. In one embodiment, a petroleumresidue comprises asphaltene. In a preferred embodiment, the contactingstep comprises removing from about 60 or 70 to about 80, 90, or 100percent by weight of asphaltene based on the asphaltene present in thepetroleum residue, although it should be appreciated that other amountsmay be removed in accordance with the present invention. The asphaltenecontent of the petroleum residue ranges from about 1 to 30 percent byweight, although it should be appreciated that other amounts may beremoved in accordance with the present invention.

For the purposes of the invention, carbon dioxide may be employed in thefluid in a liquid, gaseous, or supercritical phase. Preferably, thefluid comprises carbon dioxide in a continuous phase, and typically hasa concentration ranging from about 10, 20, 30, or 40 to about 60, 70,80, 90 or up to 100 percent by weight of carbon dioxide. If liquid CO₂is used, the temperature employed during the process is preferably below31° C. If gaseous CO₂ is used, it is preferred that the phase beemployed at high pressure. As used herein, the term “high pressure”generally refers to CO₂ having a pressure from about 500 to about 5,000psi. In a preferred embodiment, the CO₂ is utilized in a “supercritical”phase. As used herein, “supercritical” means that a fluid medium isabove its critical temperature and pressure, i.e., above about 31° C.and above about 71 bar (1,073 psi) for CO₂. The thermodynamic propertiesof CO₂ are reported in Hyatt, J. Org. Chem. 49: 5097-5101 (1984);therein, it is stated that the critical temperature of CO₂ is about 31°C.; thus the method of the present invention may be carried out at atemperature above 31° C. A preferred pressure of the carbon dioxidecontaining fluid ranges from about 1000 psi to 3000 psi.

Other optional components may be used in the fluid containing carbondioxide, the selection of which is known to one skilled in the art.Examples of other components include, without limitation, co-solvents,surfactants, co-surfactants, buffers, rheology modifiers, biologicalagents, and viscosity reduction modifiers. Other components may be usedin the carbon dioxide containing fluid, the selection of which may bedetermined by the skilled artisan. The components that may be added toCO₂ include but are not limited to gases such as, nitrogen, oxygen,argon, helium, nitrogen dioxide, methane, ethane, propane, butane, andhydrogen sulfide, alcohols such as, methanol, ethanol, isopropanol,n-propanol, and the like, ethers, such as, dimethyl ether, methyl-ethylether, methyl-isopropyl ether and the like, polymers, specially thosethat are soluble in CO₂ such as polysiloxanes, fluorinated polymers suchas, poly(hexafluoropropylene oxide) poly(vinyledenefluoride),sugar-containing diblock fluorocopolymers,Bis(perfluoro-2-N-propoxypropionyl) peroxide and fluorosurfactants suchas, poly(1,1-dihydroperfluorooctyl acrylate),PS-b-poly(dimethylsiloxane) and 1,1-dihydroperfluorooctylacrylate-hexamethylcyclotrisiloxane diblock copolymer. It is alsocontemplated that gases other than CO₂ could be employed. For example,hydrocarbon gases such as methane, ethane or argon or mixtures thereofcan be used.

The removal of petroleum residue from the substrate may be carried outby using known equipment. The solvent, for example, may be applied tothe substrate by using known and accepted systems. In a preferredembodiment, the application of the benzoic acid ester-containing solventtypically takes place from about 1 to about 20 min, at a temperatureranging from about 10° C. to about 50° C. With respect to asphaltcleaning for example, the solvent is typically sprayed under pressure onthe residue-containing tools that are placed on a perforated gridcapable of filtering the solvent from the inorganic solvent-insolublecontaminants. The filtered solvent is stored in containers for furthertreatment with CO₂.

Embodiments encompassing the use of the fluid containing carbon dioxidemay take place in a number of vessels, cells, or other delivery systems,the selection of which is known to one skilled in the art. For example,the extraction of the petroleum residue may be carried out eitherbatchwise, continuously, or semi-continuously, in appropriately designedreaction vessels or cells. Additional features may be employed such as,for example, agitation devices (e.g., a paddle stirrer or impellerstirrer) and heaters (e.g., a heating furnace or heating rods). Thesevessels or cells may be modified in accordance with the scope of thepresent invention, particularly in view of the specific substrate.

In general, the methods of the present invention may employ solvents forremoving petroleum residue in a number of varied applications. Examplesof such applications include, without limitation:

Agricultural applications, such as: cattle sprays, dampproofing andwaterproofing buildings and structures, disinfectants, fence postcoating, mulches, mulching paper, paved barn floors, barnyards, feedplatforms, and the like, protecting tanks, vats, and the like,protection for concrete structures, tree paints, water and moisturebarriers (above & below ground), wind and water erosion control, andweather modification areas. Buildings and building applications, suchas: floors, e.g., damp-proofing and water-proofing building andstructures, floor compositions, tiles and coverings, insulating fabrics,papers, step treads; roofing, e.g., building papers, built-up roofadhesives, felts, primes, caulking compounds, cement waterproofingcompounds, cleats for roofing, glass wool compositions, insulatingfabrics, felts, papers, joint filler compounds, laminated roofing,shingles, liquid roof coatings, plastic cements, and shingles; walls,siding, ceilings, e.g., acoustical blocks, compositions, felts,architectural decoration, bricks, brick siding, building blocks, papers,damp-proofing coatings, compositions, insulating board, fabrics, felts,paper, joint filler compounds, masonry coatings, plaster boards, putty,asphalt, siding compositions, soundproofing, stucco base, and wallboard;hydraulics and erosion control applications, e.g., canal linings,sealants, catchment areas, basins, dam groutings, dam linings,protection, dike protection, ditch linings drainage gutters, structures,embankment protection, groins, jetties, levee protection, mattresses forlevee and bank protection, membrane linings, waterproofing, ore leachingpads, reservoir linings, revetments, sand dune stabilization, sewagelagoons, oxidation ponds, swimming pools, waste ponds, and waterbarriers; industrial applications, e.g., aluminum oil compositions usingasphalt backed felts, conduit insulation, lamination, insulating boards,paint compositions, papers, pipe wrapping, roofing, shingles,automotive, acoustical compositions, felts, brake linings, clutchfacings, floor sound deadeners, friction elements, insulating felts,panel boards, shim strips, tacking strips, underseal, electrical,armature carbons, windings, battery boxes, carbons, electricalinsulating compounds, papers, tapes, wire coatings, junction boxcompound, molded conduits, compositions, black grease, buffingcompounds, cable splicing compound, embalming, etching compositions,extenders, rubber, other, explosives, fire extinguisher compounds, jointfillers, lap cement, lubricating grease, pipe coatings, dips, jointseals, plastic cements, plasticizers, preservatives, printing inks, welldrilling fluid, wooden cask liners, impregnated, treated materials,armored bituminized fabrics, burlap impregnation, canvas treating,carpeting medium, deck cloth impregnation, fabrics, felts, mildewprevention, packing papers, pipes and pipe wrapping, planks, rugs,asphalt base, saw dust, cork, asphalt composition, textiles,waterproofing, tiles, treated leather, wrapping papers, paints,varnishes, etc, acid-proof enamels, mastics, varnishes, acid-resistantcoatings, air-drying paints, varnishes, anti-corrosive & anti-foulingpaints, anti-oxidants and solvents, base for solvent compositions,baking and heat resistant enamels, boat deck sealing compound, lacquers,japans, marine enamels, belting, blasting fuses, briquette binders,burial vaults, casting molds, clay articles, clay pigeons, depilatory,expansion joints, flower pots, foundry cores, friction tape, gaskets,imitation leather, mirror backing, phonograph records, rubber, moldedcompounds, shoe fillers, soles, table tops, airport runways, taxiways,aprons, etc., asphalt blocks, brick fillers, bridge deck surfacing,crack fillers, curbs, gutters, drainage ditches, floors for buildings,warehouses, garages, etc., highways, roads, streets, shoulders, parkinglots, driveways, pcc underseal, roof-deck parking, sidewalk, footpaths,soil stabilization, ballast-treatment, curve lubricant, dust laying,paved ballast, sub-ballast, paved crossings, freight yards, stationplatforms, rail fillers, railroad ties, tie impregnating, stabilization,paved surfaces for: dance pavilions, drive-in movies, gymnasiums, sportsarenas, playgrounds, school yards, race tracks, running tracks, skatingrinks, swimming & wading pools, tennis courts, handball courts, crudeoil spills, wildlife cleanup, and tar sand separation.

In another embodiment, the invention relates to a method for determiningthe quantity of bitumen present in a petroleum residue sample comprisingbitumen. The method comprises contacting the petroleum residue samplewith a GRAS solvent to remove the bitumen therefrom. The weight of thebitumen in the sample is determined by comparing the initial weight ofthe petroleum residue and the weight of the remaining portion of thepetroleum residue. In a preferred embodiment, a remaining portion of thepetroleum residue is present in the form of inorganic material.

The method of determining the quantity of bitumen present in a petroleumresidue sample may include other optional embodiments. As an example,the petroleum residue comprises bitumen and inorganic material, andwherein the inorganic material remains subsequent to the step ofcontacting the petroleum residue sample with a GRAS solvent, the methodfurther comprising contacting the inorganic material at least once withan organic solvent to remove GRAS solvent from the petroleum residuesample. Preferably, the inorganic material is contacted several timeswith the organic solvent.

A number of organic solvents may be employed in the above method.Exemplary organic solvents include, without limitation, C₁-C₄ alcohols.A preferred organic solvent is ethanol.

Optionally, the method of determining the quantity of bitumen present ina petroleum residue sample may also include various other steps setforth herein, including without limitation, those involving carbondioxide. As an example, in one embodiment, the method further comprisingthe step of contacting the benzoic acid ester-containing solventcomprising petroleum residue with a fluid comprising carbon dioxide,wherein the petroleum residue is recovered in the fluid such that thebenzoic acid ester-containing solvent is separated from the petroleumresidue.

The invention will now be described in greater detail with respect tothe examples that follow. It should be understood that these examplesare set forth merely for illustrating the invention, and do not limitthe scope of the invention as defined by the claims.

EXAMPLE 1 Experimental Protocol For Single-Batch Extraction Experimentsof Tar Sand Samples Using CO₂

A tar sand sample is placed in a high-pressure 20 mL capacity reactor.The reactor is heated to the desired temperature, the system ispressurized with CO₂ at 10 mL/min flow rate until the desired pressureis reached by means of a high-precision syringe pump. The system is leftfor 1 hr at the desired temperature and pressure after which CO₂ and theextracted bitumen is conveyed under pressure to another reactor suppliedwith sapphire windows (view-cell) at a rate of 10 mL/min. After coolingthe extract to ambient temperature, CO₂ is slowly discharged from thesystem at a rate of 1 mL/min. The system is thereafter opened, theextracted bitumen is collected quantitatively by dissolving in MeCl₂,and the solvent is evaporated in a vacuum oven at 50° C. for 24 hrs.

The mass of the extracted bitumen is calculated and the percentageextraction is obtained. The total bitumen content of the sample isdetermined by MeCl₂ extraction.

EXAMPLE 2 Experimental Protocol For Single-Batch Extraction Experimentsof Asphalt Samples Using CO₂

The procedure according to Example 1 is repeated except that an asphaltsample is employed instead of a tar sand sample.

EXAMPLE 3 Experimental Protocol For Single-Batch Extraction Experimentsof Bitumen Samples Using CO₂

The procedure according to Example 1 is repeated except that a bitumensample is employed instead of a tar sand sample.

EXAMPLE 4 Extraction of Bitumen From Tar Sands Using Esters

A bitumen sample, either subjected to extraction with CO₂, or withoutbeing subjected to CO₂ extraction, is placed in a Buchner funnel. Theester solvent or solvent mixture is added continuously until the colorof the liquid did not changed, indicating complete bitumen extraction.The solution of bitumen in the aromatic ester solvent, or solventmixture, is then charged in a high-pressure view cell. CO₂ ispressurized at a specified flow rate until the desired pressure isreached using a precision syringe pump. The temperature is maintainedand controlled at the set temperature by means of a thermostated heatingtape. The system is stirred by means of a magnetic stirrer. The systemis left to equilibrate until there was no more bitumen precipitationobserved through the sapphire windows of the view cell. When apparentcomplete precipitation of bitumen occurred, the compressed gas isallowed to discharge into a series of cooled traps, where CO₂ isseparated from the ester solvent. When the system was completelydepressurized from CO₂, the precipitated bitumen is retrieved andquantified.

EXAMPLE 5 Isopropyl Salicylate Miscibility in Carbon Dioxide

The miscibility of isopropyl salicylate is evaluated in liquid, gaseous,or supercritical carbon dioxide under a number of conditions using highpressure equipment. Carbon dioxide is determined to be completelymiscible with isopropyl salicylate at the following conditions: 1:1,1:2, 1:3, 1:4, 1:5, 2:1, 3:1, 4:1, and 5:1, CO₂: isopropyl salicylatevol.:vol. ratios, at the following temperatures: 25, 35, 45, and 60° C.,and at the following pressures: 500, 1000, 1500, 2000, 2500, 3000, 3500,4000, 4500, and 5000 psi.

EXAMPLE 6 Experimental Protocol For Multiple-Batch ExtractionExperiments Using CO₂

An asphalt sample is placed in a high-pressure 20 mL capacity reactor.The reactor is heated to the desired temperature and then pressurizedwith CO₂ to the desired pressure at 10 mL/min flow rate by means of ahigh-precision syringe pump. The system is left for 1 hr at the desiredtemperature and pressure after which CO₂ and the extracted bitumen isconveyed under pressure to another reactor supplied with sapphirewindows (view-cell) at a rate of 10 mL/min followed by another transferto a second view cell in the same manner. After cooling the extract toambient temperature, CO₂ is slowly discharged from the system at a rateof 1 mL/min, the system is repressurized as described in the abovesteps. The process is repeated six times and the residence time for eachstep is fixed at 15 min. At the end of the sixth extraction, the systemis opened, and the extracted bitumen is collected from both of the twoview cells quantitatively by dissolving in MeCl₂. The solvent is thenevaporated in a vacuum oven at 50° C. for 24 hrs. The mass of theextracted bitumen is then calculated and the percentage extraction isobtained.

The total bitumen content of asphalt is obtained by MeCl₂ extraction.

EXAMPLE 7 Extraction of Bitumen From Tar Sands Using a Benzoic AcidEster

A bitumen sample, either subjected to extraction with CO₂, or withoutbeing subjected to CO₂ extraction, is placed in a Buchner funnel. Thebenzoic acid ester solvent or solvent mixture is added continuouslyuntil the color of the liquid did not change, indicating completebitumen extraction. The solution of bitumen in the solvent is thencharged in a high-pressure view cell. CO₂ is pressurized at a specifiedflow rate until the desired pressure is reached using a precisionsyringe pump. The temperature is maintained and controlled at the settemperature by means of a thermostated heating tape. The system isstirred by means of a magnetic stirrer. The system is left toequilibrate until there is no more bitumen precipitation observedthrough the sapphire windows of the view cell. When apparent completeprecipitation of bitumen occurred, the compressed gas is allowed todischarge into a series of cooled traps, where CO₂ is separated from thearomatic ester solvent. When the system is completely depressurized fromCO₂, the precipitated bitumen is retrieved and quantified.

EXAMPLE 8 Effect of Temperature on Bitumen Precipitation

The effect of temperature on the removal of bitumen from a benzoic acidester-containing solvent by employing a carbon dioxide fluid ismeasured. The bitumen is present in the solvent in an amount of 4wt./vol/percent. The bitumen is present in the solvent in a 1:3 ratio.As can be seen from FIG. 1, the amount of precipitated bitumen decreasedwith temperature for a given pressure value.

EXAMPLE 9 Effect of Concentration on Bitumen Precipitation

The effect of bitumen concentration in a benzoic acid ester-containingsolvent on subsequent precipitation in a carbon dioxide fluid isevaluated. The precipitation runs are carried out at 35° C. for a 2 hrresidence time within a reactor that is mixed with a magnetic stirrer.

As seen from FIG. 2, bitumen precipitation in the carbon dioxide fluidincreased as a function of solvent concentration.

EXAMPLE 10 Bitumen Precipitation from Benzoic Acid Ester-ContainingSolvent as a Function of Carbon Dioxide Density

The precipitation of bitumen is evaluated as a function of carbondioxide density at various temperatures ranging from 35° C. to 55° C.and pressures ranging from 2000 psi to 4000 psi. The residence time is 2hr.

As illustrated by FIG. 3, the amount of bitumen that is precipitatedincreases as a function of carbon dioxide density.

EXAMPLE 11 Effect of Benzoic Acid Ester-Containing Solvent-to-CarbonDioxide Fluid Ratio On Bitumen Precipitation

The effect of benzoic acid ester-containing solvent-to-carbon dioxidefluid ratio on bitumen precipitation is evaluated at 35° C. As seen fromFIG. 4, the amount of precipitated bitumen increased as the ratio ofsolvent to carbon dioxide fluid decreased.

EXAMPLE 12 Comparison Between Single and Multiple Extraction of Bitumenin Carbon Dioxide

A comparison between a single batch extraction and a multiple batchextraction of bitumen in carbon dioxide is illustrated in FIG. 5. Thestudy is carried out at 25° C. As seen, the multiple batch extractionsprovided for higher yields of extracted bitumen.

EXAMPLE 13 Comparison Between Single and Multiple Extraction of Bitumenin Carbon Dioxide

The procedure according to Example 12 is repeated except that thetemperature is set at 35° C. The results are shown in FIG. 6. Ingeneral, the yields are higher in comparison to Example 10.

EXAMPLE 14 Comparison Between Single and Multiple Extraction of Bitumenin Carbon Dioxide

The procedure according to Example 12 is repeated except that thetemperature is set at 50° C. The results are shown in FIG. 7. Ingeneral, the yields are higher in comparison to those set forth inExamples 12-13.

EXAMPLE 15 Comparison Between Single and Multiple Extraction of Bitumenin Carbon Dioxide

The procedure according to Example 12 is repeated except that thetemperature is set at 80° C. The results are shown in FIG. 8. Ingeneral, the yields are higher in comparison to those set forth inExamples 12-14.

EXAMPLE 16 Comparison Between Single and Multiple Extraction of Bitumenin Carbon Dioxide

The procedure according to Example 12 is repeated except that thetemperature is set at 100° C. The results are shown in FIG. 9. Ingeneral, the yields were higher in comparison to those set forth inExamples 12-14.

EXAMPLE 17 Benzoic Acid Ester Solvent Cleaning Measurement

1 g bitumen was weighed in a 20 mL capacity transparent glass vial capedwith PTFE caps. 5 mL of the solvent to be tested was transferred to thevial, caped, and shaken by hand, with the amount of dissolved bitumenwas visually inspected every minute. The time at which the last tracesof bitumen disappeared was recorded as the time taken for completebitumen dissolution. If the entire bitumen sample dissolved, theconcentration of the bitumen in the solution may reach 20 wt/vol percentwhich is a relatively high concentration. The results obtained fromthese experiments are summarized in Table 1:

TABLE 1 Solubility No Sample Name in Minutes Remarks 1 Pave Pro(Edgecombe 15 Complete Solubility County) Generated Appreciable Amountof Foam 2 HTF-959-B (Wilson 22 Incomplete Solubility County) 3 Orangeasphalt Remover 17 Complete Solubility (Nash County) 4 Big Orange E(Edgecombe 22 Incomplete Solubility County) 5 Pure and Natural Orange 22Incomplete Solubility Bean (Specially Formulated) 6 Invention 12Completely Soluble No (IPB) Foam Was GeneratedThe solution employed in the method of the invention (No. 6) is the mostefficient solvent for bitumen as it was the fastest to dissolve the 1 gsample in 12 minutes. The Pave Pro solvent (No. 1) dissolved the 1 g ofbitumen in 15 minutes. Nonetheless, No. 6 is distinguished from No. 1 bythe fact that it doesn't foam when it was shaken. Conversely, No. 1produced a high foam column when it was shaken. According to theDepartment of Transportation (DOT) guidelines, it is highly recommendedthat the solvent does not produce foam as this will potentially decreaseits efficiency when it is applied by sprayers. Such a decrease is oftenexperienced when these solvents are used in cleaning asphalt-pavingequipment.

EXAMPLE 18 Bitumen Extraction from Asphalt

An asphalt sample obtained from Texaco Petroleum Company of Houston,Tex. was contacted with a solution of IPB for approximately 15 min. at atemperature of about 25° C. A maximum concentration of 23.71 wt./vol.percent of bitumen in the IPB was achieved. Such a result comparedfavorably with a 26.40 wt./vol. percent concentration of bitumen in aconventional solution of methylene chloride.

EXAMPLE 19 Extraction of Bitumen in Carbon Dioxide as a Function ofTemperature and Pressure (Single-Batch)

Bitumen was extracted using a carbon dioxide containing fluid, and theeffect on fluid temperature and pressure was evaluated. An asphaltsample (5 g) was loaded into a high-pressure 20 mL capacity reactor. Thereactor was heated to the desired temperature. The system waspressurized with carbon dioxide at a rate of 10 mL/min until the desiredpressure was reached by means of a high-pressure syringe pump. Thesystem was left for 1 hr at the desired temperature and pressure afterwhich carbon dioxide and the extracted bitumen was conveyed underpressure to another reactor supplied with sapphire windows (view-cell)at a rate of 10 mL/min. After the extract was cooled to ambienttemperature, the carbon dioxide was slowly discharged from the system ata rate of 1 mL. The system was thereafter opened, the extracted bitumenwas collected quantitatively by dissolution in methylene chloride, andsubsequently the solvent was evaporated in a vacuum oven at 50° C. for24 hrs. The mass of extracted bitumen was calculated and the percentextracted was thus obtained. The total bitumen content of asphalt wasdetermined by methylene chloride extraction.

The extractions were each carried out for a one hour residence time. Theresults of the extraction are set forth in FIG. 10. As exhibited, theamount of extracted bitumen increased as a function of both temperatureand pressure.

EXAMPLE 20 Extraction of Bitumen in Carbon Dioxide as a Function ofTemperature and Pressure (Multiple Extractions)

Various asphalt samples were placed in a high-pressure 20 mL capacityreactor. The reactor was heated to the desired temperature and thenpressurized with carbon dioxide to the desired pressure at a flow rateof 10 mL/min by means of a high-precision syringe pump. The system wasleft at 1 hr at the desired temperature and pressure after which CO₂ andthe extracted bitumen was conveyed under pressure to another reactorsupplied with sapphire windows (view-cell) at a rate of 10 mL/minfollowed by another transfer to a second view cell in the same manner.After cooling the extract to ambient temperature, CO₂ was slowlydischarged from the system at a rate of 1 mL/min. The system wasrepressurized in the manner described above, and the process wasrepeated six times. The residence time for each step was held constantat 15 min. At the end of the sixth extraction, the system was opened andthe extracted bitumen was collected from both view cells quantitativelyby dissolution in methylene chloride. The solvent was thereafterevaporated in a vacuum oven at 50° C. for 24 hours. The mass of theextracted bitumen was then calculated and the percentage extraction wasobtained. The total bitumen content of asphalt was obtained by methylenechloride extraction.

The results of the multiple extraction runs are illustrated in FIG. 11.In general, extraction quantity increased as a function of temperatureand pressure. A maximum of 94.96 weight percent of bitumen was extractedat a pressure of 5000 psi and a temperature of 100° C.

EXAMPLE 21 Extraction with Supercritical Carbon Dioxide

An asphalt paving sample (to the nearest 0.1 mg) is placed in ahigh-pressure reactor. The reactor is pressurized with CO₂ at a pressureranging from 1000 to 5000 psi and the temperature is adjusted andmaintained at the set temperature ranging from 25 to 120° C. The systemis left to equilibrate for the appropriate residence time after whichthe pressurized gas is allowed to pass onto a collecting cooled trap.CO₂ is slowly vented from the trap at a flow rate of 1 mL/min leavingthe extracted bitumen in the trap which is quantified by weighing thetrap before and after extraction. The process may be repeated for 6times to extract the maximum amount of bitumen.

EXAMPLE 22 Extraction with the Benzoic Acid Ester Containing Solvent

The residue which is left in the high-pressure reactor after extractionwith CO₂ according to Example 21 is mixed with the benzoic acid estercontaining solvent using a mechanical stirrer mounted over the reactor.The solvent-to-sample ratio ranges from 2:1 to 5:1 volume-to-mass ratio.Although not intending to be bound by theory, it is believed that such aratio depends on the amount of bitumen present in the sample.

The solvent is added in 4 to 6 aliquots until the solvent venting thesystem becomes colorless. In a preferred embodiment, the solvent ventingthe cell is filtered from the inorganic insoluble particles constitutingpart of the asphalt paving mixture using online filters with 0.2μ poresize. The refractive index of the filtrate is measured by arefractometer until the refractive index of the solvent is exactly thesame as that of the pure solvent to insure that bitumen is fullyextracted from the sample.

EXAMPLE 23 Precipitating Bitumen from the Benzoic Acid Ester ContainingSolvent

The solution of bitumen in the benzoic acid ester containing solventobtained according to Example 22 is placed in a high-pressure reactorsupplied with a sapphire view cell. The system is pressurized with a CO₂specific pressure (1000-5000 psi), temperature (25-120° C.), andresidence time (5-120 min) that will efficiently precipitate thebitumen, preferably all of the bitumen. CO₂, plus the dissolved benzoicacid ester containing solvent is allowed to vent from the system to acollecting vessel at a flow rate of 1 mL/min. The system is washedseveral times with CO₂ to solubilize the benzoic acid ester containingsolvent and the residue is dried under vacuum and quantified. CO₂ isseparated from the benzoate solvent by depressurizing and cooling thesystem. The total extracted bitumen is quantified as the sum of thebitumen extracted from CO₂ and that extracted by the benzoic acid estercontaining solvent.

EXAMPLE 24 Analytical Determination of Bitumen in Asphalt Sample

An asphalt paving mixture sample weighed to the nearest 0.1 mg is placedin the extraction thimble of a soxhlet extractor apparatus. The benzoicacid ester-containing solvent is heated to boiling and the condensedliquid extracts the bitumen from the asphalt paving mixture sample. Theprocess is stopped when the solvent dripping from the extraction thimbleis rendered colorless. The inorganic material left in the extractionthimble is then rinsed several times with ethanol, dried until constantmass, and weighed to the nearest 0.1 mg. The mass of the extractedbitumen is obtained by subtracting the mass of the residual inorganicsfrom the mass of the asphalt sample determined before the extractionstep.

EXAMPLE 25 Analytical Determination of Bitumen in Asphalt Sample

The procedure according to Example 16 is repeated except that an asphaltpaving mixture is placed in a Buchner funnel, rinsed with a benzoic acidester-containing solvent until the solvent is rendered colorless. Thebenzoic acid ester-containing solvent containing the extracted bitumenis subjected to a carbon dioxide-containing fluid for precipitating thebitumen and recycling the solvent.

EXAMPLE 26 Benzoic Acid Ester Miscibility Study

CO₂ was found to be miscible with isopropyl benzoate at the followingconditions: 1:1, 1:2, 1:3, 1:4, 1:5, 2:1, 3:1, 4:1, and 5:1, CO₂:isopropyl benzoate vol.:vol. ratios, at the following temperatures: 25,35, 45, and 60° C., and at the following pressures: 500, 1000, 1500,2000, 2500, 3000, 3500, 4000, 4500, and 5000 psi, as determined usingknown procedures.

EXAMPLE 27 Analytical Determination of Bitumen in Large Asphalt Sample

An asphalt paving mixture sample weighed to the nearest 0.1 mg is placedin the Ploog Engineering Co. Centrifuge apparatus. The benzoic acidester-containing solvent is heated to boiling and the condensed liquidis run through the centrifuge and extracts the bitumen from the asphaltpaving mixture sample. The process is stopped when the solvent drippingfrom the centrifuge is rendered colorless. The inorganic material leftin the centrifuge is then rinsed several times with ethanol, dried untilconstant mass, and weighed to the nearest 0.1 mg. The mass of theextracted bitumen is obtained by subtracting the mass of the residualinorganics from the mass of the asphalt sample determined before theextraction step.

EXAMPLE 28 Bitumen Extraction from Asphalt

An asphalt sample was contacted with a solution of isopropyl salicylatefor approximately 15 min. at a temperature of about 25° C. A maximumconcentration of 23.71 wt./vol. percent of bitumen in the isopropylsalicylate was achieved. Such a result compared favorably with a 26.40wt./vol. percent concentration of bitumen in a conventional solution ofmethylene chloride.

EXAMPLE 29 Extraction with Supercritical Carbon Dioxide

An asphalt paving sample (to the nearest 0.1 mg) is placed in ahigh-pressure reactor. The reactor is pressurized with CO₂ at a pressureranging from 1000 to 5000 psi and the temperature is adjusted andmaintained at the set temperature ranging from 25 to 120° C. The systemis left to equilibrate for the appropriate residence time after whichthe pressurized gas is allowed to pass onto a collecting cooled trap.CO₂ is slowly vented from the trap at a flow rate of 1 mL/min leavingthe extracted bitumen in the trap which is quantified by weighing thetrap before and after extraction. The process may be repeated for 6times to extract the maximum amount of bitumen.

EXAMPLE 30 Extraction with the Ester-Containing Solvent

The residue which is left in the high-pressure reactor after extractionwith CO₂ according to Example 29 is mixed with the ester-containingsolvent using a mechanical stirrer mounted over the reactor. Thesolvent-to-sample ratio ranges from 2:1 to 5:1 volume-to-mass ratio.Although not intending to be bound by theory, it is believed that such aratio depends on the amount of bitumen present in the sample.

The solvent is added in 4 to 6 aliquots until the solvent venting thesystem becomes colorless. The solvent venting the system is filteredfrom the inorganic insoluble particles constituting part of the asphaltpaving mixture using online filters with 0.2 μm pore size. Therefractive index of the filtrate is measured by a refractometer untilthe refractive index of the solvent is exactly the same as that of thepure solvent to insure that bitumen is fully extracted from the sample.

EXAMPLE 31 Precipitating Bitumen from the Ester-Containing Solvent

The solution of bitumen in the ester-containing solvent obtainedaccording to Example 30 is placed in a high-pressure reactor suppliedwith a sapphire view cell. The system is pressurized with a CO₂ specificpressure (1000-5000 psi), temperature (25-120° C.), and residence time(5-120 min) that will efficiently precipitate the bitumen, preferablyall of the bitumen. CO₂, plus the dissolved ester-containing solvent isallowed to vent from the system to a collecting vessel at a flow rate of1 mL/min. The system is washed several times with CO₂ to solubilize theester-containing solvent and the residue is dried under vacuum andquantified. CO₂ is separated from the solvent by depressurizing andcooling the system. The total extracted bitumen is quantified as the sumof the bitumen extracted from CO₂ and that extracted by theester-containing solvent.

EXAMPLE 32 Analytical Determination of Bitumen in Asphalt Sample

An asphalt paving mixture sample weighed to the nearest 0.1 mg is placedin the extraction thimble of a soxhlet extractor apparatus. Theester-containing solvent is heated to boiling and the condensed liquidextracts the bitumen from the asphalt paving mixture sample. The processis stopped when the solvent dripping from the extraction thimble isrendered colorless. The inorganic material left in the extractionthimble is then rinsed several times with ethanol, dried until constantmass, and weighed to the nearest 0.1 mg. The mass of the extractedbitumen is obtained by subtracting the mass of the residual inorganicsfrom the mass of the asphalt sample determined before the extractionstep.

EXAMPLE 33 Analytical Determination of Bitumen in Asphalt Sample

The procedure according to Example 32 is repeated except that an asphaltpaving mixture is placed in a Buchner funnel, rinsed with anester-containing solvent until the solvent is rendered colorless. Theester-containing solvent containing the extracted bitumen is subjectedto a carbon dioxide-containing fluid for precipitating the bitumen andrecycling the solvent.

EXAMPLE 34 Solubility Study of Ester-Containing Solvent in CarbonDioxide

The miscibility of CO₂ with isopropyl salicylate was evaluated. CO₂ wasfound to be miscible with isopropyl salicylate at the followingconditions: 1:1, 1:2, 1:3, 1:4, 1:5, 2:1, 3:1, 4:1, and 5:1, CO₂:isopropyl salicylate vol.:vol. ratios, at the following temperatures:25, 35, 45, and 60° C., and at the following pressures: 500, 1000, 1500,2000, 2500, 3000, 3500, 4000, 4500, and 5000 psi.

Having thus described certain preferred embodiments of the presentinvention, it is to be understood that the invention defined by theappended claims is not to be limited by particular details set forth inthe above description as many apparent variations thereof are possiblewithout departing from the spirit or scope thereof as hereinafterclaimed.

1. A method for determining the percent of bitumen present in apetroleum residue sample, said method comprising: contacting thepetroleum residue sample with a first, ester-containing solvent toremove the bitumen therefrom, and wherein the weight of the bitumen inthe sample is determined by comparing the initial weight of thepetroleum residue and the weight of a remaining portion of the petroleumresidue; wherein the petroleum residue comprises bitumen and inorganicmaterial, and wherein the inorganic material remains subsequent to saidstep of contacting the petroleum residue sample with an ester-containingsolvent; and wherein the remaining portion comprises the inorganicmaterial and further comprising contacting the remaining portion atleast once with a second, different, organic solvent, prior to weighingthe remaining portion.
 2. The method according to claim 1, wherein thecontacting of the remaining portion at least one of removes remaining1^(st) solvent from the sample, is conducted more than once or isfollowed by drying of the remaining portion prior to weighing of theremaining portion.
 3. The method according to claim 1 wherein theorganic solvent is a C1-C4 alcohol.
 4. The method according to claim 3wherein the organic solvent is ethanol.
 5. The method according to claim4 wherein the petroleum residue is an asphalt residue.
 6. The methodaccording to 1, further comprising the step of contacting theester-containing solvent with a fluid comprising carbon dioxide, whereinthe petroleum residue is recovered in the fluid such that theester-containing solvent is separated from the petroleum residue.
 7. Themethod according to claim 1, further comprising removing theester-containing solvent with heat after the contacting step.
 8. Amethod for determining the percent of bitumen in a petroleum residuesample containing bitumen and inorganic material, said methodcomprising: (a) weighing the petroleum residue sample; (b) contactingthe petroleum residue sample with an ester-containing solvent to removesubstantially all of the bitumen therefrom; (c) contacting the samplewith a second, different solvent to remove remaining ester-containingsolvent from the sample; (d) weighing the inorganic material remainingin the sample; (e) determining the percentage of bitumen in the samplebased on the results of steps (a) and (c).
 9. The method according toclaim 8, further comprising the step of contacting the ester-containingsolvent with carbon dioxide to recover the ester-containing solvent.